The kid wasn't a runner, he was the batter. Most likely there was a steal and an overthrow allowing the runner to come home. Little kids tend to watch the plays and not get out of the way. Plus he was holding the bat.

the ump is a dumbass for one reason: yes, the kid was in the way but the ump THREW him. he could have easily gotten the kid out of the way without tossing him on his ass. this is little league, not the pros... they dont know wtf they're doing. the ump is a douchenozzle.